This invention relates to hydronic heating and/or cooling systems for dwellings, offices, etc. having heating or cooling loops that consist of tubing or pipes fed hot or cold water, held in the floor, walls or ceiling of a room by panels that contain a metal radiation plate that: radiates heat to the room when the tubing is fed hot water, to heat the room; or absorbs heat from the room by radiation when the tubing is fed cold water, to cool the room; the tubing being secured in the panels in intimate thermal contact with the radiation plate and covered by a finished floor, wall or ceiling of the room. In particular, the installation includes special adaptations that improve performance for heating and cooling and avoid hot and/or cold spots on the surface of the finished floor, wall or ceiling and avoids condensation on the finished floor, wall or ceiling when cooling during humid conditions.